Analog to digital translators



Nov. 1, 1960 J. LUONGO ETAL ANALOG To DIGITAL TRANsLAToRs Filed NOV. 9, 1956 Inventum .Jost-Pff Ua/v60 ,WCHA/ea f/f/VRY RYMER f/eA/vk A ram/f); JR. BW@ g/M A Home y United States Patent O ANALOG T DIGITAL TRANSLATORS Joseph Luongo, Cedar Grove, and Richard Henry Rymer, Belleville, NJ., and Frank P. Turvey, Jr., Melboum, Fla., assignors to International Telephone and Telegraph Corporation, Nutley, NJ., a corporation of Maryland Filed Nov. 9, 1956, Ser. No. 621,399 "I Claims. (Cl. 340-347) This invention relates` generally to analog to digital translators and in particular to devices for translating shaft rotations into electrical coded pulses.

Originally the translation devices or digitizers, Wherein the end product was in an electrical pulse form, were of the commutating variety, and many of these types of translation devices are still widely used. These commfutating digitizers have a segment representing each number and a read brush coupled to a common brush. The read brush can be positioned on each segment to effect a digitizer readout. The commutator digitizer has some inherent disadvantages in that the timing of `the read brushes must be exact and tolerances therefore must be close, lest there can be a false number read out from the device. For instance, in reading out the numbers 39, 40 and 41, and assuming a respective readout position for the units and tens position, it is conceivable that if the brushes did not read exactly together, but instead one brush led the other, the translation might read 39, 30, 40, and 41, or 39, 49, 40 `and 41. To overcome this problem there is brought into use the lead and lag brush. The lead and lag brushes are set respectively far ahead and far behind the normal readout point, and by reading from the lag brush up to a carry time and from the lead brush at and beyond the carry time there is insured a non-ambiguous readout. It is clear that to accomplish the lead and lag readout there must be a controlling device. Since, generally, the digitizers involved are of the decimal form, the controls are accomplished by having commutator straps of 180 added 4to the shafts. By controlling relays with these cornmutator straps and having the readout pass through these relays, it is possible to have either a lead or a lag readout for one half the shaft rotation. It also becomes clear that the abovementioned commutator strap, with its inherent mechanical characteristics in combination with the relays, gives rise to considerations of mechanical tolerances and speed limitations, the improvement of which is desirable for the higher speed operations such as those desired in analog computers or high speed control systems.

The schemes described above have been used in systems wherein the language is of decimal form and since the language of many modern computers is in coded binary form, it is desirable to provide such a system for a coded translation.

It is therefore the object of this invention to provide an improved information translation device.

It is a further object of this invention to provide a translation device which requires only the code means of the machine as its basis for a lead or lag readout control.

It is a further object of this invention to provide a high speed translation device wherein there are no mechanical or speed limitations resulting from relays or commutator controls.

In accordance with a main feature of our invention, we use the code wheel output itself in the dual role of providing intelligence signals for further use as well as the basis for controlling the selection of the lead or lag readout means. In accordance with a feature of our invention -there is provided a matrix means which is responsive to the code wheel output and in response thereto selects either the lead or lag readout means, as Well as a particular bit on the wheel being read, which in turn is read by lthe selected readout means.

The above mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings which show `a system using a reflected binary code and in which:

Fig. 1 is a combination schematic and block diagram showing the readout for three of the code wheels;

Fig. 2 shows the developed pattern of the strips on a coded wheel and the accompanying binary representation and decimal values.

In Fig. 1 there are three code wheels shown at 10, 11 and 12. To code wheels 11 and 12 there are connected respectively four lead read brushes 13 and 14 and respectively four lag brushes 15 and 16. To code wheel 10 there is connected four read brushes 17 which are neither lagging or leading. The read brushes 13 through 17 are connected to the scan matrix 18. The input diodes 19 through 22 are connected to the scan generator 23 by input lines 24 through 27. The input lines 29 and 30 of -the and gate 28 are respectively connected to the input line 27 and to the read matrix output 31. The output 31 is shunted -by load resistance 31a which is connected to ground as shown. The and gate 28 output line 32. is connected to the input of the lead-lag selector 33 whose outputs 34 and 35 are connected to the input diodes 36 and 37. The read matrix 11 is connected to the scan generator 23 through the read generator 38 and to the code Wheels 10, 11 and 12, respectively, through the common inputs 39, 40 and 41. The upper portion of the switching matrix is connected to a plurality of load resist-- ances 41 to 48 which are in turn tied to B+. The clock pulses shown at 49 represent the pulses being generated at the scan lgenerator 23 and passed to the input lines 24 through 27.

In Fig. 2 the code wheel pattern at 50 is a developed bit pattern from a code wheel using reflected binary code. Adjacent to the bit pattern in the tables shown at 51 and 52 are representative binary codes and the decimal values.

In Fig. l let us assume that there has been set up in decimal coded binary form, and appearing on the code wheels 10, 11 and 12, the number 299. Let us further assume that the number 299 represents the speed of an aircraft and that the speed is being recorded or sent to a computer for an automatic control. Let us make a further assumption that the speed of the aircraft increases and there appears successively on the coded wheels the numbers 300 and 301. Working with these assumptions we must first examine the code wheels 10, 11 and 12. On code Wheel 10, the Wheel of least significant decimal order, under the brushes 17 there would appear 1010 or'from Fig. 2 combine-d with Fig. l metal bits under brushes 53 and 54 and no metal bits under brushes 55 and 56. Since the readout from code wheel 10 controls the lead or lag readout from code wheel 11, we should first examine the code wheel 10 readout. The read matrix 11 may be any well-known parallel to serial readout matrix. The read generator 38 in combination with the read matrix 11 provides selecting circuitry means by which the code wheel 10 is selected for the iirst readout. The least significant bit on the wheel 10 is under brush 56, this is clear from Fig. 2. The scan generator 23 conditions line 24 with a positive pulse T-1. This positive pulse attempts to lift the vo-ltage condition at points 51 and 58. We will assume that the lag side of the lead-lag selector 33 is conducting. The inputs from the scan generator 23 and the lead-lag selector 33, in Icombination, act as an and gate. It follows that 4if the lag side of 33 is conducting then the point 58 is down and the point 57 is up. With point S7 up, the B+ appears at the bottom side off the resistance 44 and hence ify there were continuity from ground through resistance 31a, the read matrix 11, along the common 39, through brush 56, through the lower diode 19, through point 57, and to B+, there would be current ow. However, since brush 56 is sitting on a blank space there is no path of continuity so there is no output pulse at 31. A readout through the bits respectively, under brush 54 and brush 55 would follow the above discussion. Considering now the readout of the most significant bit, we find there is continuity from ground to B+ since brush 53 is sitting on a metal bit as discussed above. It follows that point S9 is up as was point 57 so there is an output in accordance with the above discussion. The clock pulse T4, having been passed to line 27, is also passed to the and gate 2S through input 29. The output pulse at 31 is also passed to the and gate 28. For a coincidence of the T4 clock pulse and a positive output pulse the selector gate 33 is conditioned to conduct on the lag side 35. For a non-coincidence of the T4 pulse and the output pulse, the selector gate 33 is conditioned to conduct on the lead side 34. Since there is coincidence in our hypothetical problem, the lag brushes 16 are readout from the tens position code wheel 11. Binary representation on code wheel 11 is also 1010, from Fig. 2, and the readout is similar to the readout described for Wheel 10. It then follows that the lag brushes 15 will be controlled to readout from code wheel 12. The binary representation on code wheel 12 is 0111 which means there are metal bits under the brushes 60, 61, 62 and therefore there are different paths of continuity. The readout from code wheel 12, with the exception of the different paths of continuity, will be the same as described for code wheel 1G. As the speed of the aircraft goes to 300 we find that code wheel 10 now has a 0010 sitting under the brushes 17. Since the readout has already been described, let us only consider the readout of the most significant bit which is sitting under brush 53. Because this most significant bit is or a non-conductive bit, there is no continuity from ground to B+, hence there is no positive output pulse at 31, and from the prior discussion a non-coincidence of the T4 pulse and the output pulse conditions the lead side 34 of the selector 33 to conduct. lt follows that point 58 would now be up for the next readout which is from code wheel 11 and therefore the lead brushes 14 would be operative. The code wheel 12 would follow in a similar pattern having the lead brushes 13 being operative because of the control from code wheel 11. When any of the wheels pass through a 4 to 5 transition on the code strip of the most significant bit, see Fig. 2, there will be a positive output pulse at 3l and the selector 33 will be flipped back to conduct on the lag side 35. From the above example it is obvious that the device insure a non-ambiguous readout, using the code as a basis for control and effects a high speed operation by means of a single switching matrix.

While we have described above the principles of our invention in connection with specific apparatus it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.

We claim:

1. A translation device for translating shaft rotations into coded electrical pulses comprising a plurality of code Wheels each assigned different order of value and each producing a different code output signal at different angular positions thereof, an input shaft, said plurality of Wheels coupled to said shaft for inter-related rotation according to a predetermined ratio, a plurality of paired lead-lag readout means with each pair coupled to an associated one of said wheels, a plurality of common output conductor with a single one each coupled to a separate associated one of said wheels, a switching matrix means coupled to said plurality of lead-lag readout means, lead-lag selector means coupled to said switching matrix means to select in combination therewith one of the coded bits to be read through a selected lead or lag readout means, and means coupling the output of said code wheels and said switching matrix means to said lead-lag selector means for sampling the pulse readout from each of said code Wheels respectively and in accordance therewith controlling said selection o-f'said lead or lag readout means for the adjacent wheel of a wheel thus sampled to eliminate a false readout at the time of complete rotation of said adjacent wheel.

2. A translation device for translating shaft rotations into coded electrical pulses comprising a plurality of code wheels each assigned a different order of value and each producing a different code output signal at different angular positions thereof, an input shaft, said plurality of wheels coupled to said shaft for inter-related rotation according to a predetermined ratio, a plurality of paired lead-lag readout means coupled to said wheels, a plurality of common outputs with one each coupled to an associated one of said wheels, a readout matrix means coupled to said plurality of common outputs for selecting one of said Wheels to be read therefrom, a switching matrix means coupled to said plurality of lead-lag readout means, lead-lag selector means coupled to said switching matrix means to select in combination therewith one of the coded bits to be read through a selected lead or lag readout means, and circuitry means to couple said readout matrix means and said switching matrix means to said lead-lag selector means for sampling the pulse readout from said readout matrix means and in accordance therewith controlling said selection of said lead or lag readout means for the adjacent wheel to eliminate a false readout at the time of complete rotation of said adjacent wheel.

3. A decimal coded binary translation device for translating shaft rotations into coded electrical pulses comprising a plurality of wheels with coded tracks thereon wherein each wheel of said plurality is assigned a different decimal order of value, an input shaft, said plurality of wheels coupled to said shaft for inter-related rotation according to a predetermined ratio, a plurality of singular readout means one each of which is coupled to one each of said coded tracks of the wheel which has been assigned the least significant value, a plurality of paired lead-lag readout means with one each of said pairs coupled to one each of said coded tracks on the wheels which have been assigned higher order Values than the least significant, a plurality of common readout means with one each coupled to an associated one of said wheels, a readout matrix means coupled to said plurality of common readout means for selecting one of said Wheels to be read therefrom, a switching matrix means coupled to said plurality of singular readout means and said plurality of lead-lag readout means, a lead-lag selector means coupled to said switching matrix means to select in conjunction therewith one of said coded tracks to be read through a selected lead or lag readout means, Vand circuitry means to couple said readout matrix means to said switching matrix means and said lead-lag selector means for sampling the pulse readout therefrom and thereby controlling said selection of said lead or lag readout means for the next higher order position to eliminate an ambiguous translation.

4. A translation device for translating shaft rotations into coded electrical pulses comprising a plurality of code wheels each assigned different order of value and each producing a different code output signal at different angular positions thereof, an input shaft, said plurality of wheels coupled to said shaft for inter-related rotation according to a pre-determined ratio, a plurality of singular readout means coupled to the one of said wheels which has been assigned the least significant value, a plurality of paired lead-lag readout means with each pair coupled to an associated one of said wheels which have been assigned higher order values than the least significant value, a plurality of common outputs with one each coupled to an associated one of said wheels, a switching matrix means coupled to said plurality of lead-lag readout means, lead-lag selector means coupled to said switching matrix means to selectin combination therewith one of the coded bits to be read through a selected lead or lag readout means, and means coupling the output of said code wheels and said switching matrix means to said lead-lag selector means for sampling the pulse readout from each of said code wheels respectively and in accordance therewith controlling said selection to said lead or lag readout means for the adjacent wheel of a wheel thus sampled to eliminate a false readout at the time of complete rotation of said adjacent wheel.

5. A translation device for translating shaft rotations into coded electrical pulses comprising a plurality of code wheels each assigned different order of value and each producing a different code output signal at different angular positions thereof wherein the code found on each code wheel is formed by conducting and non-conducting strips such that the most significant code bits form a continuous strip of conducting material having a given number of degrees of their respective track position and bounded by a non-conducting strip, an input shaft, said plurality of wheels coupled to said shaft for inter-related rotation according to a pre-determined ratio, a plurality of paired lead-lag readout means with each pair coupled to an associated one of said wheels, a plurality of common outputs with one each coupled to an associated one of said wheels, a switching matrix means coupled to said plurality of lead-lag readout means, lead-lag selector means coupled to said switching matrix means to select in combination therewith one of the coded bits to be read through a selected lead or lag readout means, and means coupling the output of said code wheels and said switching matrix means to said lead-lag selector means for sampling the pulse readout from each of said code wheels respectively and in accordance therewith controlling said selection of said lead or lag readout means for the adjacent wheel of a wheel thus sampled to eliminate a false readout at the time of complete rotation of said adjacent wheel.

6. A translation device for translating shaft rotations into coded electrical pulses comprising a plurality of code wheels each assigned different order of value and each producing a different code output signal at different angular positions thereof, an input shaft, said plurality of wheels coupled to said shaft for inter-related rotation according to a pre-determined ratio, a plurality of paired lead-lag readout means with each pair coupled to an associated one of said wheels, a plurality of common outputs with one each coupled to an associated one of said wheels, a switching matrix means coupled to said plurality of lead-lag readout means, said switching matrix including a clock pulse generator, a lead-lag selector means coupled to the output of said clock pulse generator of said switching matrix means to select in combination therewith one of the coded bits to be read through a selected lead or lag readout means, and means coupling the output of said code wheels and said switching matrix means to said lead-lag selector means for sampling the pulse readout from each of said code wheels respectively and in accordance therewith controlling said selection of said lead or lag readout means for the adjacent wheel of a wheel thus sampled to eliminate a false readout at the `time of complete rotation of said adjacent wheel.

7. A translation device for translating shaft rotations into coded electrical pulses comprising a plurality of code wheels each assigned different order of value and each producing a different code output signal at different angular positions thereof, an input shaft, said plurality of wheels coupled to said shaft for inter-related rotation according to a pre-determined ratio, a plurality of paired lead-lag readout means with each pair coupled to an associated one of said wheels, a plurality of common outputs with one each coupled to an associated one of said Wheels, a switching matrix means coupled to said plurality of lead-lag readout means, said switching matrix including a clock pulse generator and a matrix coupled to the output of said clock pulse generator, lead-lag selector means coupled to the input said matrix of said switching matrix, means, said matrix of said switching matrix means forming an and gate for selecting a lead or lag readout means in accordance with the outputs of said clock pulse generator and said lead-lag selector means and also forming a switching arrangement for the selection of coded bits to be read through said selected lead-lag readout means in further response to said outputs, and means coupling the output of said code wheels and said switching matrix means to said lead-lag selector means for sampling the pulse read-out from each of said code wheels respectively and in accordance therewith controlling said selection of said lead or lag readout means for the adjacent wheel of a wheel thus sampled to eliminate a false readout at the time of complete rotation of said adjacent wheel.

References Cited in the file of this patent UNITED STATES PATENTS 2,750,584 Goldscher June l2, 1956 2,779,539 Darlington Ian. 29, 1957 2,826,252 Dickstein Mar. l1, 1958 2,866,184 Gray Dec. 23, 1958 OTHER REFERENCES `Electronic Equipment, August 1955, p. 13. 

